Re: [PATCH RFC] reduce runqueue lock contention

[Oleg Nesterov]

On 12/13, Frank Rowand wrote:
>
> I have not been able to make sense of the task_running() check in
> try_to_wake_up(), even with that clue.  The try_to_wake_up() code in
> question is:
> ...
>
> What am I missing, or is the task_running() test not needed?

I am afraid I can misuderstood this all, including the question ;)

But, with __ARCH_WANT_UNLOCKED_CTXSW task_running() checks ->oncpu.
However, schedule() drops rq->lock after prev was deactivated but
before it clears prev->oncpu.

Oleg.

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